yes it's "supported" the same as Hibernate ORM, remember it shares most of the code to manage state, up to the point it needs to synchronize with the used databse.,

The context of execution is local (managed entities within some scope, like Hibernate ORM, typically the transactional scope however not all NoSQL databases have real transactions so let's call it "scope").

On top of the local scope it can use distributed / clustered 2nd level caching. This might not be needed as most NoSQL stores are pretty fast, but the cache layer can be local so you have that option.

Some datastores support clustering, for example if you use Cassandra or Infinispan their architecture was designed to be clustered. When you use such a datastore obviously OGM can take advantage of it.